The structure of agar

Duckworth, M.; Yaphe, W.

doi:10.1016/s0008-6215(00)86113-3

Cited by 340 publications

(63 citation statements)

References 18 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…For the more concentrated polymer system, it was suggested that the change of the relaxation time depended upon the change of local viscosity. 6 In a dilute system such as studied here, the adsorption of uranine on the agarose chain was suggested to be more important in determining the value of 1/p, 4 and this was confirmed quantitatively, as shown in Figure 9. Although adsorption sites on agarose chain by uranine were not confirmed in detail at this point, these should not be negatively charged kink segments, but the neutral helix segments.…”

Section: Adosorption Of Uranine On Agarose Macromoleculesupporting

confidence: 64%

“…"Difeo Bacto Agar" was also used to obtain fractionated samples, which were the same samples as used in Yaphe's work. 6 FITC-conjugated agarose was prepared according to the usual method.…”

Section: Methodsmentioning

confidence: 99%

“…6 The 486 fraction F-1 was the cold water extractive, corresponding to the agaropectin rich in substituents. The fraction F-2 was the warm (55°C) water extractive which contained less substituents than F-1.…”

Section: Methodsmentioning

confidence: 99%

See 2 more Smart Citations

Studies of the Agarose Gelling System by the Fluorescence Polarization Method. II.

Hayashi

Kinoshita

Kuwano

et al. 1978

Polym J

View full text Add to dashboard Cite

The sol-gel transformation of agarose and other polysaccharide fractions from agar were investigated by the fluorescence polarization method in order to study the gelling mechanism of agarose. The results showed that the gelation in dilute systems was a cooperative process of a helix segment with a kink segment in the agarose. In the process, the role of the helix segment was interpreted on the basis of Flory's mechanism for the transition and phase equilibria of asymmetric polymers. That is, the helix segment folded into a rodlike helical chain at the helix point to form an isotropic solution. At the gel point, the isotropic solution was separated into the tactoidal concentrated solution phase (coacervate) and the isotropic more dilute solution phase. The coacervate droplets were joined to each other with the non-helical kink segment to form a three-dimensional network structure. The rodlike helical chain tended to aggregate into the crystalline phase, though the rate was fairly slow just below the helix point because of the nucleation controlled process. Some of the helical chains still tended to aggregate into the crystalline phase in the coacervate. The melting point of the gel corresponded to that of the crystalline phase, and was higher than the gel setting point. The hysteresis of the agarose sol-gel transformation was thus interpreted by the difference between the melting point and the setting point.

show abstract

Section: Adosorption Of Uranine On Agarose Macromoleculesupporting

confidence: 64%

“…"Difeo Bacto Agar" was also used to obtain fractionated samples, which were the same samples as used in Yaphe's work. 6 FITC-conjugated agarose was prepared according to the usual method.…”

Section: Methodsmentioning

confidence: 99%

See 1 more Smart Citation

Studies of the Agarose Gelling System by the Fluorescence Polarization Method. II.

Hayashi

Kinoshita

Kuwano

et al. 1978

Polym J

View full text Add to dashboard Cite

show abstract

“…Fractionation studies on DEAE Sephadex A-50 carried out by DUCKWORTH and YAPHE [217], [220] have indicated that agar is not made of one neutral and one charged polysaccharide but is composed of a complex series of related polysaccharides which range from a virtually neutral molecule to a highly charged galactan. These studies indicated that in agars containing 4,6-O-(1-carboxyethylidene)-D-galactose, this charged residue is always found in regions of the molecule with low sulfate content.…”

Section: Structure and Gelling Mechanismmentioning

confidence: 99%

Polysaccharides

Voragen

Rolin²,

Marr³

et al. 2003

Ullmann's Encyclopedia of Industrial Chemistry

View full text Add to dashboard Cite

The article contains sections titled: 1. Introduction 2. Analysis and Characterization 3. Pectin 3.1. Occurrence and Structure 3.2. Pectolytic Enzymes 3.3. Production 3.4. Properties 3.4.1. Physical Properties 3.4.2. Gel Properties 3.4.3. Stability and Chemical Reactions 3.5. Analysis 3.5.1. Measurement and Standardization of Gel‐Forming Capacity 3.5.2. Chemical Analysis 3.6. Pharmaceutical and Nutritional Characteristics 3.7. Application in the Food Industry 3.8. Market 4. Alginates 4.1. Occurrence 4.2. Production 4.3. Structure 4.4. Properties 4.5. Propylene Glycol (Propane‐1,2‐diol) Alginate 4.6. Bacterial Alginates 4.7. Analysis 4.8. Applications 4.9. Market 5. Carrageenan 5.1. Structure 5.2. Sources and Raw Materials 5.3. Production 5.4. Analysis 5.5. Properties 5.6. Applications 5.7. Physiological Properties 6. Agar 6.1. Production 6.2. Structure and Gelling Mechanism 6.3. Quick Soluble Agar 7. Gum Arabic 8. Gum Tragacanth 9. Gum Karaya 10. Gum Ghatti 11. Xanthan Gum 11.1. Production 11.2. Structure and Properties 11.3. Analysis 11.4. Applications, Market 12. Gellan Gum 13. Galactomannans 13.1. Structure 13.2. Production 13.3. Properties 13.4. Analysis and Composition of Commercial Preparations 13.5. Derivatives 13.6. Applications 13.7. Market 14. Acknowledgement

show abstract

“…la). The agarose backbone is substituted at irregular intervals with charged groups such as carboxylate, pyruvate, and sulfate [23]. @-Carrageenan, a stereoisomer of agarose, is an alternating copolymer of 1,3-linked 0-D-galactose (A residue) and 1,Clinked 3,6-anhydro-a-D-galactose (B residue) [24] (Fig.…”

Section: -16]mentioning

confidence: 99%

“Flip‐flop” orientation of agarose gel fibers in pulsed alternating electric fields

Stellwagen

1993

Electrophoresis

View full text Add to dashboard Cite

The orientation of the agarose gel matrix in pulsed electric fields has been studied by transient electric birefringence. Two types of agarose with different degrees of charge were studied, in addition to agarose solutions and gels containing beta-carrageenan, a stereoisomer of agarose, and polyacrylamide. Agarose gels exhibit normal orientation behavior when short, high voltage pulses are applied to the gel. The sign of the birefringence is positive and the relaxation times are consistent with the orientation of dangling fiber ends parallel to the electric field. When long, low voltage pulses, of the amplitude and duration used for pulsed field gel electrophoresis, are applied to the gel, completely different orientation effects are observed. The amplitude of the birefringence (i.e., extent of orientation) is much larger than expected from the high field results, and the birefringence decay curves contain multiple components of opposite sign. The relaxation times are consistent with the orientation of long agarose chain bundles or fibers, as well as large three-dimensional domains. Chain bundles or fibers of the lengths observed in the agarose gels are also observed in agarose solutions, suggesting that the fibers that are free to orient in the gels had previously formed in the sol phase and are only weakly integrated into the matrix structure. In rapidly reversing low voltage electric fields, the sign of the birefringence of the agarose gels reverses from positive to negative in phase with the reversing electric field. This alternating change in the sign of the birefringence suggests that the agarose fibers "flip-flop" in orientation from parallel to perpendicular every time the electric field reverses its direction. Similar effects are observed for agarose gels with different charge densities. The flip-flop orientation and reorientation of agarose fibers within the matrix in reversing electric fields may decrease the microscopic viscosity of the gel, increasing the mobility of large DNA molecules migrating through the gel during electrophoresis. Polyacrylamide gels do not exhibit an anomalous reversal of the sign of the birefringence in reversing electric fields. Hence, the orienting fibers in these gels do not change their direction of orientation in reversing electric fields. Extensive orientation is observed in beta-carrageenan gels, similar to that observed in agarose gels. However, little orientation occurs in polyacrylamide gels, which are chemically crosslinked.(ABSTRACT TRUNCATED AT 400 WORDS)

show abstract

The structure of agar

Cited by 340 publications

References 18 publications

Studies of the Agarose Gelling System by the Fluorescence Polarization Method. II.

Studies of the Agarose Gelling System by the Fluorescence Polarization Method. II.

Polysaccharides

“Flip‐flop” orientation of agarose gel fibers in pulsed alternating electric fields

Contact Info

Product

Resources

About